What should the standard library of drill bits available at the DMS be? What should the mix of drill bits be?
Here is my guess at the list:
These numbers and distribution is based on common hole sizes for different screws as well what is commonly found in drill bit sets. And downright guessing
If you think any sizes are missing please let me know. I also did not put any letter size drill bits on the list as I did not see any use for them outside of specialized applications. If you know of any lettered drill bit sizes that are important to have please let me know.
F and H are the standard drill sizes for close fit and free fit clearance holes (respectively) for 1/4-20 screws. Plus P/Q for 5/16" and W/X for 3/8" âŚ
EDIT: If we add in the tap drills for the major threads up to 1/2", then the following lettered drills would be required: F, H, I, J, L, P, Q, S, T, U, W, X, Y, Z
Are these just for the general logistics table use, or are they for everything? Machine shop would need a bunch of additional sizes.
This has been a very heated discussion in Machine Shop committee meetings. Currently we are leaning on the fractional size & sizes for taps.
Why? Well itâs expensive & difficult to keep track of 300 different sizes, especially given most makers tolerances are not that tight.
I think that is the advantage of having a solid selection of general use set of drill bits. The most heavily used sizes will be covered thus minimizing the likelihood of people abusing the more specialized sizes in the machine shop.
I believe we have a pretty complete set of taps in the machine shop area.
I donât think it makes sense to cover all the sizes this should be 20% of sizes that are used 80% of the time or as close to that ideal as we can get.
Let me clarify. I really meant that we should check and see which of the larger taps we have. We might or might not have anything larger than 1/4". And if we donât, then thereâs no need to worry about the lettered drills for those sizes.
The following is relevant to Logistics/General Workshop only
Going to speculate that the selection we provide can be rather coarse as the primary use case is drilling pilot- and through-holes in wood for common lag screws and bolts. #6, #8, #10, #12, Âź", â ", ½" probably a strong - if not overwhelming - majority of what youâre going to see hand tools used for.
Itâs good to have other sizes for general use, but that strikes me as extremely low priority. If theyâre included in variety packs, cool, weâll stock them since those seem to have lower unit costs than buying individual sizes.
Edit: Accomodating #4 and #20 lag screws (~5/16") :
Number
Dec Dia
Cloest Frac Dia
HW straight
SW Straight
#4
.112"
7/64"
5/64"
1/16"
#6
.138"
9/64"
7/64"
3/32"
#8
.164"
5/32"
1/8"
7/64"
#10
.190"
3/16"
9/64"
1/8"
#14
.242"
1/4"
11/64"
5/32"
#20
.320"
5/16"
15/64"
7/32"
⌠we could focus on the following sizes, adding â " and ½" as through-holes for bolts.
Frac
Dec
1/16"
0.0625
5/64"
0.0781
3/32"
0.0938
7/64"
0.1094
1/8"
0.1250
9/64"
0.1406
5/32"
0.1563
11/64"
0.1719
3/16"
0.1875
7/32"
0.2188
15/64"
0.2344
1/4"
0.2500
5/16"
0.3125
3/8"
0.3750
1/2"
0.5000
In my experience, there will be high breakage rates on 1/16" through 1/8", moderate breakage rates 9/64" thru 15/64", low breakage rates 1/4" thru 1/2".
Not giving consideration to metric because in my experience metric lag screws and bolts are vanishingly rare at hardware stores and wood doesnât demand the tolerances of metal.
I agree with the concept you are presenting. Basically, IMO it makes sense for DMS to have on hand a set of sizes similar to what a moderately well stocked home based hobby maker would have. Something on the order of the sizes you can buy in a reasonably available mid-sized case from a store. Machine shop might logically have a different list since they are the ones more likely to need to tap metal, etc.
In either case, DMS has provided a good selection of commonly used drill bits. Then if a Maker needs a unique size for a one-off project ⌠they can go buy that bit on demand. For what it is worth, I use this approach on the Multicam ⌠stock the common needs, especially if I can source them inexpensively, and let Makers get their own specialty bits & mills.
I agree that we should go heavy on the really common sizes but I think having a solid selection of the in between sizes is important. I have slimmed the list down to 36 individual drill bit sizes. These sizes will give us solid coverage of most applications.
I have reached out to a few suppliers and gotten quotes back.
The set seems to be coming in at ~$80 or ~$0.35 per drill bit. However most of these quotes have really high MOQs. I am still talking to some other suppliers to see if we can get the MOQs down to something reasonable.
I got a solid quote back today for ~$87 for the 218 drill bits so about ~$0.40 cents each on average.
I have attached the quote for everyone to take a look at. The MOQ is 10 cases or ~$870 + shipping + tax. This order would be for a total of 2180 drill bits. I am willing to put $200 of my money in on this.
Logistics would want some secure storage before committing to that kind of purchase - no point in laying that kind of abundance out just to watch the shrinkage happen.
